For a causal relationship to exist there must be evidence group of answer choices of an empirical correlation between the variables. that one variable precedes the other in time. that a third variable did not cause the changes observed in the first two variables. that one variable precedes the other in time and that the two variables are correlated. that one variable precedes the other in time, that the two variables are correlated and that this relationship is not spurious.

that one variable precedes the other in time, that the two variables are correlated and that this relationship is not spurious.

Explanation:

In Experimental and Quasi-Experimental Designs for Generilized Causal Inference (2002), researchers Cook and Campbell present a set of conditions that must be met in order to establish a valid causal relationship: one variable precedes the other in time (temporal precedence), the two variables are correlated (covariation), and that this relationship is not spurious (no third variable is present).

There is no correlation because the relationship is not linear

Explanation:

answer; ///i believe the correct answer is (b) the writing of the ancients who lived in india after the indus valley inhabitants died out;

they had freedom from the government and from the affairs